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Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico)
Department of Biology, University of Puerto Rico, P.O. Box 9012, Mayagüez, PR 00681, Puerto Rico
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA
* Author to whom correspondence should be addressed.
Received: 15 November 2005; Accepted: 3 July 2006 / Published: 30 September 2006
Abstract: Hydrocarbon contamination of groundwater resources has become a major environmental and human health concern in many parts of the world. Our objectives were to employ both culture and culture-independent techniques to characterize the dynamics of microbial community structure within a fluidized bed reactor used to bioremediate a diesel-contaminated groundwater in a tropical environment. Under normal operating conditions, 97 to 99% of total hydrocarbons were removed with only 14 min hydraulic retention time. Over 25 different cultures were isolated from the treatment unit (96% which utilized diesel constituents as sole carbon source). Approximately 20% of the isolates were also capable of complete denitrification to nitrogen gas. Sequence analysis of 16S rDNA demonstrated ample diversity with most belonging to the ∝, β and γ subdivision of the Proteobacteria, Bacilli, and Actinobacteria groups. Moreover, the genetic constitution of the microbial community was examined at multiple time points with a Functional Gene Array (FGA) containing over 12,000 probes for genes involved in organic degradation and major biogeochemical cycles. Total community DNA was extracted and amplified using an isothermal φ29 polymerase-based technique, labeled with Cy5 dye, and hybridized to the arrays in 50% formimide overnight at 50°C. Cluster analysis revealed comparable profiles over the course of treatment suggesting the early selection of a very stable microbial community. A total of 270 genes for organic contaminant degradation (including naphthalene, toluene [aerobic and anaerobic], octane, biphenyl, pyrene, xylene, phenanthrene, and benzene); and 333 genes involved in metabolic activities (nitrite and nitrous oxide reductases [nirS, nirK, and nosZ], dissimilatory sulfite reductases [dsrAB], potential metal reducing C-type cytochromes, and methane monooxygenase [pmoA]) were repeatedly detected. Genes for degradation of MTBE, nitroaromatics and chlorinated compounds were also present, indicating a broad catabolic potential of the treatment unit. FGA’s demonstrated the early establishment of a diverse community with concurrent aerobic and anaerobic processes contributing to the bioremediation process.
Keywords: Bioremediation; functional gene microarray; biofilm; tropical environments
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Rodríguez-Martínez, E.M.; Pérez, E.X.; Schadt, C.W.; Zhou, J.; Massol-Deyá, A.A. Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico). Int. J. Environ. Res. Public Health 2006, 3, 292-300.
Rodríguez-Martínez EM, Pérez EX, Schadt CW, Zhou J, Massol-Deyá AA. Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico). International Journal of Environmental Research and Public Health. 2006; 3(3):292-300.
Rodríguez-Martínez, Enid M.; Pérez, Ernie X.; Schadt, Christopher W.; Zhou, Jizhong; Massol-Deyá, Arturo A. 2006. "Microbial Diversity and Bioremediation of a Hydrocarbon-Contaminated Aquifer (Vega Baja, Puerto Rico)." Int. J. Environ. Res. Public Health 3, no. 3: 292-300.